chore: use 8 character hash components

[stevenh]

Use 8 character hash components to reduce the key length, making it more readable.

Fixes #97

[stevenh]

This is stacked on top of #142

Example output from test run with hash-length: 8

Restore Key:
      v0-rust-test-08480e93
  Cache Key:
      v0-rust-test-08480e93-e9d0959e

[Swatinem]

I would just always truncate this to 8 chars (aka 4 bytes of hash value) instead of making it configurable.

This is not supposed to be a cryptographic hash, even in the unlikely case of a 1-in-4-billion collision, the worst thing that can happen is that the build is taking a longer time because it does not have the right artifacts. So what 🤷🏻‍♂️

[stevenh]

I would just always truncate this to 8 chars (aka 4 bytes of hash value) instead of making it configurable.

This is not supposed to be a cryptographic hash, even in the unlikely case of a 1-in-4-billion collision, the worst thing that can happen is that the build is taking a longer time because it does not have the right artifacts. So what 🤷🏻‍♂️

The reason I made it configurable was to keep compatible with existing caches. Yes this would be one time change when it pulls the new version and for small projects the impact wouldn't be to bad, but for large projects it could cause noticeable delays.

As this is more a quality of file change and all other caches use the full hash, felt like keeping the standard hash as the default would be the best course. Thoughts?

[Swatinem]

for small projects the impact wouldn't be to bad, but for large projects it could cause noticeable delays

A cache by definition is best-effort. There is never a guarantee, just a hit-rate to optimize for, so a full rebuild every once in a while does not hurt. :-)

[stevenh]

Will update this once we have the key stability PR landed😊

[max-sixty]

Thanks @stevenh !